chore(core): introduce elligator2 feature flag

core/SConscript.firmware

@@ -17,6 +17,7 @@ FEATURE_FLAGS = {
     "RDI": True,
     "SECP256K1_ZKP": True,  # required for trezor.crypto.curve.bip340 (BIP340/Taproot)
     "SYSTEM_VIEW": False,
+    "ELLIGATOR2": False,
 }
 
 FEATURES_WANTED = ["input", "sbu", "sd_card", "rgb_led", "dma2d", "consumption_mask", "usb" ,"optiga"]
@@ -110,7 +111,6 @@ SOURCE_MOD += [
     'vendor/trezor-crypto/ed25519-donna/ed25519-sha3.c',
     'vendor/trezor-crypto/ed25519-donna/ed25519.c',
     'vendor/trezor-crypto/ed25519-donna/modm-donna-32bit.c',
-    'vendor/trezor-crypto/elligator2.c',
     'vendor/trezor-crypto/groestl.c',
     'vendor/trezor-crypto/hasher.c',
     'vendor/trezor-crypto/hmac.c',
@@ -368,6 +368,12 @@ if FEATURE_FLAGS["SYSTEM_VIEW"]:
     CPPDEFINES_MOD += ['SYSTEM_VIEW']
     CCFLAGS_MOD += '-DSYSTEM_VIEW '
 
+if FEATURE_FLAGS["ELLIGATOR2"]:
+    CPPDEFINES_MOD += ['USE_ELLIGATOR2']
+    SOURCE_MOD += [
+        'vendor/trezor-crypto/elligator2.c',
+    ]
+
 # fonts
 tools.add_font('NORMAL', FONT_NORMAL, CPPDEFINES_MOD, SOURCE_MOD)
 tools.add_font('BOLD', FONT_BOLD, CPPDEFINES_MOD, SOURCE_MOD)

core/SConscript.unix

@@ -23,6 +23,7 @@ if TREZOR_MODEL in ('DISC1', ):
 
 FEATURE_FLAGS = {
     "SECP256K1_ZKP": True,  # required for trezor.crypto.curve.bip340 (BIP340/Taproot)
+    "ELLIGATOR2": True,
 }
 
 CCFLAGS_MOD = ''
@@ -113,7 +114,6 @@ SOURCE_MOD += [
     'vendor/trezor-crypto/ed25519-donna/ed25519-sha3.c',
     'vendor/trezor-crypto/ed25519-donna/ed25519.c',
     'vendor/trezor-crypto/ed25519-donna/modm-donna-32bit.c',
-    'vendor/trezor-crypto/elligator2.c',
     'vendor/trezor-crypto/groestl.c',
     'vendor/trezor-crypto/hasher.c',
     'vendor/trezor-crypto/hmac.c',
@@ -171,6 +171,12 @@ if FEATURE_FLAGS["SECP256K1_ZKP"]:
         'vendor/trezor-crypto/zkp_bip340.c',
     ]
 
+if FEATURE_FLAGS["ELLIGATOR2"]:
+    CPPDEFINES_MOD += ['USE_ELLIGATOR2']
+    SOURCE_MOD += [
+        'vendor/trezor-crypto/elligator2.c',
+    ]
+
 # modtrezorio
 SOURCE_MOD += [
     'embed/extmod/modtrezorio/modtrezorio.c',

core/embed/extmod/modtrezorcrypto/modtrezorcrypto.c

@@ -52,7 +52,9 @@ static void wrapped_ui_wait_callback(uint32_t current, uint32_t total) {
 #include "modtrezorcrypto-crc.h"
 #include "modtrezorcrypto-curve25519.h"
 #include "modtrezorcrypto-ed25519.h"
+#if USE_ELLIGATOR2
 #include "modtrezorcrypto-elligator2.h"
+#endif
 #include "modtrezorcrypto-groestl.h"
 #include "modtrezorcrypto-hmac.h"
 #include "modtrezorcrypto-nist256p1.h"
@@ -97,8 +99,10 @@ STATIC const mp_rom_map_elem_t mp_module_trezorcrypto_globals_table[] = {
      MP_ROM_PTR(&mod_trezorcrypto_curve25519_module)},
     {MP_ROM_QSTR(MP_QSTR_ed25519),
      MP_ROM_PTR(&mod_trezorcrypto_ed25519_module)},
+#if USE_ELLIGATOR2
     {MP_ROM_QSTR(MP_QSTR_elligator2),
      MP_ROM_PTR(&mod_trezorcrypto_elligator2_module)},
+#endif
 #if !BITCOIN_ONLY
     {MP_ROM_QSTR(MP_QSTR_monero), MP_ROM_PTR(&mod_trezorcrypto_monero_module)},
 #endif

core/src/trezor/crypto/__init__.py

@@ -4,12 +4,16 @@ from trezorcrypto import (  # noqa: F401
     bip39,
     chacha20poly1305,
     crc,
-    elligator2,
     hmac,
     pbkdf2,
     random,
 )
 
+try:
+    from trezorcrypto import elligator2  # noqa: F401
+except Exception:
+    pass
+
 from trezor import utils
 
 if not utils.BITCOIN_ONLY: